Washington: Researchers suggest that excessive consumption of protein for building muscle mass could have a negative impact on the body. However, wide-range of protein is best to maintain balance.

Amino acids have long been touted by the fitness and bodybuilding communities for their muscle building benefits. From ultra-bulk protein powders to lean mass-promoting snack bars, there's no shortage of products available for those seeking a muscle boost.

However, protein's popularity has also meant that less attention has been paid to researching its potentially negative side-effects. According to the study published in the Journal of Nature Metabolism, excessive consumption of branched-chain amino acids (BCAAs) may reduce lifespan, negatively impact mood and lead to weight gain.

BCAAs stand for branched-chain amino acids. It's a group of three essential amino acids: leucine, isoleucine and valine, and are most commonly found in red meat and dairy. BCAAs great for adding muscle mass, but science says you could pay for it later.

Researchers have investigated the complex role nutrition plays in mediating various aspects of metabolic health, reproduction, appetite and ageing. "While diets high in protein and low in carbohydrates were shown to be beneficial for reproductive function, they had detrimental effects for health in mid-late life, and also led to a shortened lifespan," one of the researchers, Dr Samantha Solon explained.

"What this new research has shown is that amino acid balance is important. It's best to vary sources of protein to ensure you're getting the best amino acid balance." The current research examined the impacts that dietary BCAAs and other essential amino acids such as tryptophan had on the health and body composition of mice.

"Supplementation of BCAAs resulted in high levels of BCAAs in the blood which competed with tryptophan for transport into the brain," explained one of the researchers, Professor Stephen Simpson.

"Tryptophan is the sole precursor for the hormone serotonin, which is often called the 'happiness chemical' for its mood-enhancing effects and its role in promoting sleep. But serotonin does more than this, and therein lay the problem," he added.

Dietitian and public health nutritionist Dr Rosilene Ribeiro recommend eating a wide range of proteins. It's important to vary protein sources in order to get a variety of essential amino acids, through a healthy and balanced diet rich in fibre, vitamins and minerals.

BCAAs are essential amino acids present in protein-containing foods, with red meat and dairy being the richest sources. Chicken, fish and eggs are also nutritious sources of BCAAs. Vegetarians can find BCAAs in beans, lentils, nuts and soy proteins.